Fluid pressure operated apparatus



April 2, 1963 C. H. HAY 3,083,730

FLUID PRESSURE OPERATED APPARATUS Filed Jan. l5, 1961 4 Sheets-Sheet 1 lmy, 7, l 1 l l CLHUDE HEN Ky HHY pril 2, 1963 c. H. HAY

FLUID PRESSURE OPERATED APPARATUS 4 Sheets-Sheei'l 2 Filed Jan. 15, 1961CLm/DE HEL/Ry HHY uw MMM/Ma #TTM/H5 pril 2, 1963 C. H. HAY

FLUID PRESSURE OPERATED APPARATUS 4 Sheets-Sheet 3 Filed Jan. 15, 1961IENVENTOKv CLAUDE Hr-wiy Hff/ 6%, 06AM/ M/ #WMA/Ew April 2, 1963 c. H.HAY 3,083,730

' FLUID PRESSURE OPERATED APPARATUS Filed Jan. 15, 1961 4 Sheets-Sheet 41 l 1f f/ @a jajjgg 2117 0% 15)@ 951325550 VTM/wf f 3,03,73 FLUlDPRESSURE @PERATED MARA'EUS Claude Henry Hay, Dartford, Kent, England,assigner to Baldwin Instrument Company Limited, Dartiord, England, aBritish company Filed lan. 13, lll, Ser. No. 82,6%@ il@ Claims. Cl.IE7-62%) This invention relates to iiuid pressure operated apparatus inwhich a main control valve is operated by a pilot piston and cylinder.The invention is applicable both to pneumatically and hydraulicallycontrolled apparatus.

In many types of uid pressure operated apparatus, a luid pressure signalfor initiating operation of the main control valve is available. In somemachines, for example, a signal pressure is oi for part of a completecycle of operation and on for the remainder of the cycle and the onsetof the signal pressure is used to initiate an operation of the maincontrol valve. It is often necessary, therefore, to ensure that the maincontrol valve can be reversed irrespective of whether the originalsignal pressure is still on or not. Heretotore this has generallynecessitated the provision of complex arrangements in which the movementof part of the apparatus operates some clearing valve to remove thesignal nid pressure from the pilot piston. For example, in an automaticdrilling machine, the signal pressure system is commonly arranged sothat the signal pressure is on for the whole cycle of operation exceptwhilst the feed system for feed ing the drill is operating, during whichperiod the signal pipe controlling the feed or" the drill unit may beopen to exhaust. As soon as the feed slide clears the drilling zone, asignal pressure is provided which is applied to the drill unit valve tooperate the drill and this signal pressure will stay on until the nextcycle. This means that the drill valve has to reverse with the pressurestill on the pilot piston. It is an object of the present invention toprovide an improved arrangement enabling the main control valve to beoperated by a signal pressure and returned subsequently irrespective ofwhether the signal pressure is still applied or not.

According to this invention there is provided duid pressure operatedapparatus in which a feed movement is initiated or effected by theapplication of a iluid pressure signal to a pilot piston, which fluidpressure operated apparatus comprises in combination a main controlvalve which is operated by the pilot piston, pressure equalising meansoperative to equalise the pressure on the two sides of the pilot pistonafter the latter is moved, under the action of the fluid pressuresignal, a predetermined distance such as to eiect operation of the maincontrol valve, and means eective to restore the pressure equalisingmeans to their inoperative condition. With this arrangement, when thesignal uid pressure is applied, the pilot piston operates the maincontrol valve, but when the pressures on the two sides of the pilotpiston are equalised, the pilot piston no longer exerts any force on themain control valve. Thus the main control valve can be reversed althoughthe signal pressure is still on. Moreover, if the pilot piston is notrigidly connected to the main control valve, the pilot piston can bemoved to a certain extent without effecting the main control valve, eventhough the signal pressure is still applied. As soon as the signalpressure has been shut ofi, however, the pressure equalising means arereturned to their inoperative condition so that subsequent applicationof signal pressure will eiiect movement of the pilot piston again. Itwill thus be seen that the signal pressure has to be shut off andrestored in order to start a further cycle of operation.

rates atet To equalise the pressures on the two sides of the pilotpiston, both sides of the latter may be opened to atrnosphere, or thesignal pressure may be applied to both of said sides. The restoration ofthe measure equalising means to their inoperative condition takes placewhen the signal pressure is shut oft", and preferably these pressureequalising or neutralising means include a diilerential piston. Thisdiierential piston may be spring-urged in the direction to seal apassage between the two sides of the pilot piston and means may beprovided effective to move the dilerential piston to open said passagewhen the pilot piston has moved a predetermined distance.

In one arrangement, the aforesaid dierential piston is movably mountedwithin the pilot piston and stop means are provided which are electiveafter a predetermined distance of movement ot' the dierential pistonwith the pilot piston to move the diierential piston relatively to thepilot piston to open said passage. Thus when the signal pressure isapplied, the pilot piston is operated but, after a predeterminedmovement, the stop means operate the dilerential piston to equalise thepressures on the two sides of the pilot piston. As soon as the signalpressure is cut oi, the differential piston under the aforesaidspring-urge will seal the passage through the pilot piston and thesystem will be ready for the next cycle of operation.

Most conveniently, the differential piston is spring-urged in thedirection of movement of the pilot piston to operate the main controlvalve, and the stop means are arranged to stop the diterential pistouand allow continued movement of the pilot piston.

Preferably means are provided for applying the signal pressure to thedilerential piston to hold that piston in the position in which saidpassage is open; thus the diterential piston is re-set when the signalpressure is shut od. This may be achieved by arranging that the movementof the differential piston relatively to the pilot pistou uncovers aport to admit the signal pressure to one side of the differential pistonto move it in opposition to the said spring-urge.

For a more complete understanding of the invention, there will now bedescribed, by way of example only, and with reference to theaccompanying drawings, certain constructional forms of iluid pressureoperated apparatus according to the invention. It is to be understood,however, that the invention is not restricted to the preciseconstructional details set forth.

In these drawings:

FlGURES l-5 are sectional views showing one coustruction according tothe invention in different settings of the parts.

FIGURES 6-S are similar views of a modied construction,

FIGURE 9 is a detail part-sectional View on an enlarged scale, ofcertain of the parts shown in FGURES 1 5, the sectional plane of FIGURE9 being at right angles to the sectional plane of FIGURES 15, and

FIGURE 1G illustrates a modification of the arrangement shown in FIGURES1 to 5 and 9.

Like reference numerals indicate like parts throughout the drawings.

Referring firstly to FIGURE-S l-5 and 9, a valve block l@ is formed witha bore to receive a main control valve 1l in annular packing members 12,`and is also formed with a larger -bore to receive a pilot piston 13,the head of which carries another annular packing member 14. rIlse blocklil has a passage 1S leading to the cylinder of the fluid pressureoperated apparatus (not shown in the drawings), which is to becontrolled and `also has two other passages 16 and 17 which can beseparately connected to the passage 15 by the valve l1 as describedbelow. The passage 16 leads from the main pressure supply and thepassage 17 leads to exhaust. There is also an axial passage 18 thefunction of which is to supply pressure to reset the valve 11. A furtherpassage 19 admits the signal pressure to the pilot piston 13, land :avent passage 20 leads from one end of the bore in which the pilot piston13 is received. v

The main control valve 11 is formed with a waist 21 past which thepassage 15 can be interconnected with either the passage 16 or Ithepassage 17 according to the position of the valve 1-1, and the annularpacking members 12 arecarried by stationary ported sleeves 22 whichpermit the said interconnection through appropriate ports and aclearance between the inner surface of the sleeves and the outside ofthe valve 1,1.

`One end portion of the valvell is bored to receive a spigot 23 on Vahead 24 which slides in a bore in the block 1 0 and carries its own,annular packing member. The head 24 is arranged to bear against the endof the valve 11. The other end portion of the valve 11 is formed with asomewhat similar bore which receives a tubular Yprojection 25 reachingaxially from the pilot piston 13, and also receives -a control spring 26which bears at one end Y against the end -face of the bore and'at theirother end againstthe end of the projection 25. The tubular pro- Vjection25 has opposed' apertures 27 in it through which reaches, with freedomfor lost motion, a cross pin 28 carried byl the valve 11 (seeparticularly FIGURE 9).

The bore in the block 10 which receives the pilot piston 13 has aninternal annular shoulder 29 spaced sufliciently from one end of thesaid bore to accommodate, and determine the limit of, the travel of thepiston head, the inner diameter of the shoulder 29 is such as to leave aclear-ance between it and the outer surface of the shank 30 of thepiston. Two other annular. packing members 31, spaced apart by astationary ported sleeve 32, are held between the shoulder v29 and theother vend of the bore in the block 10, `and closely engage the outersurface of the piston shank 30.

The piston shank 30 is tubular 'and has a port 33 which in all positionsof the piston 13 is in communication with the passage 19 Vfwhich admitsthe signal pressure. The piston shank 30 also has another port 34 whichis close to lthe piston head. yThe function of the port 34 is describedbelow. The end of the piston shank A3ft carries a tubular extension 35,and received in the interior of 'the parts 30 and 35 is adifferentialpiston comprising a body 36 and a head 37, The bore of the piston shank30 carries three annular packing vmembers m1-separated by ported sleeves4'5 which lare allocated to the ports 33 and 34. The packing members 44are alwaysrin engagement *with* the bore of the piston shank and attimes certain of them are in engagement with the external surface ot'Ythe differential piston body 36 to make a seal therewith. g This pistonbody 36 has a waist 38 and its end remote from the Yhead 37 yis extendedin the form of a pin 39 Iwhich reaches into lthe interior of theprojection 25 from the vpilot piston. The head `37 'of the diierentialpiston 36 is grooved at 40 to receive an annular packing member 41 toseal against the interior of the extension 35 incertain relativepositions of the pilot piston and the diierential piston. The end ofthetubular extension 35 is closed by a plate 42 between which and the head37 of the diierential piston a spring 43 is situated. The pilot piston13 is formed with Ya passage 46 which extends from the end face of thepilot piston to the bore in the latter.

The operation of the construction according to the invention shown inFIGURES land 9 may beV described as follows. In FIGURE l, the maincontrol valve 11 and the pilot piston 13 are located at the right handlimit of their travel ,and the differential piston 36 is 1ocated at theleft hand limit of its travel. The passage 15, leading to the cylinderin the fluid pressure apparatus being controlled, is connected totheexhaust passage 17.

4 Signal pressure in the passage 419 will pass through the port 33 tothe interior of the pilot piston shank 30, thence to the port 34 and out-to the left of the shoulder 29 to move the pilot piston 13 to theposition shown in FIGURE 2. During this movement the projection 25 onthe pilot piston, bearing against the spring 26, will correspondinglymove the main control valve 11 to the position shown in FIGURE 2, inwhich the passage 1:5 is cut ott from both of the passages 16 and 17.=In FIGURE 3, the main control valve 11 has lreached the left hand limitof its travel, but the pilot piston 13 has not yet done this and isbeing urged to the left by the signal pressure. The passage 15 is stillcut o from `the passage 17 but is open to the supply passage 16. InFIGURE 4, the pilot piston 13 has taken up the lost motion, between itandthe main control valve 11, permitted by the apertures Y2,7 tou-thecross pin 28, and has compressed the spring 26. The passage 15 is stillopen to the passage 16 and closed to the Vpassage 17. The pin 39extending from the dilerd ential piston 36 has encountered the cross pin-28 thus causing the dilerent-ial piston 36 to be moved to the rightwith respect to the pilot piston 13. As the result of this, the signalpressure from passage 19 is now shut 0E from the head of the pilotpiston but is permitted Yto reach the left hand face of the head 37 Vofthe diie'rentia'l piston. Signal pressure uid remains trapped in thespace between the shoulder 29 and the opposed end of the pilot pistonhead. In FIGURE 5, -the signal pressure on the head of the diierentialpiston has moved the latter further to the right, compressing the spring43. As Vthe result of this movement, which may be quite sudden, thesignal pressure lluid trapped in the space between the shoulder 29 andthe opposed end of the pilot piston head is able to pass throughV theport 34 to the passage 46 and thus to the vent 20. The spring 26 has inconsequence been able to restore vthe relative positions of the maincontrol valve and the pilot piston'to that lshown in A.FIG- URE 3. Thepressure on both sides ofthe Apilot piston having been equalised, viz.,opened to atmosphere, reversing pressuregapplied through the passage 18will reset the main control valve and the pilot piston. soon as thesignal pressure in the passage y19 is 'shut Voft, Vthe spring 43 willreturn the differential piston to the position shown in FIGURE l. Untilthis has occurred the cycle of operation cannot recommence. y

The construction shown in FIGURES 6-8, is in some respects similar tothe construction shown in FIG- URES 1-5 and 9. However, a `differentform of main control valve 47 is shown, and the bore inthe pilot piston13 only has two annular packing members '44. The body of thedifferential piston 36 does not have any waistv but it has an internalconduit 48 which opens at one end into the interior of the extension 35of the .pilot piston shank, and at the other end to the surface of aportion 49 of the diierential piston -36 larger than the aforesaid pin39. There is no vent passage corresponding With the passages 20in'FIGURES l-5.

The construction shown in FIGURES '6-8, operates, in some respects, inexactly the same way as the 'construction shown in FIGURES 1-5 and 9.The setting Vshown in FIGURE 6 corresponds withthat shown in FIGURE l,the setting shown in FIGURE 7 corresponds with that shown in FIGURE 4,and the setting Yshtiwr'i in FIGURE 8 corresponds with that shownrinFIGURE 5. The equalisation of the pressure on the two sides o'f'tliepilot piston 13 is elected, as shown in FIGURES 7 and 8, by applying thesignal pressure to both of said sides, through the port 34 and thepassage 46 respectively. The Vpassage 48 enables the signal pressure tocomplete the movement of the differential piston 36 to the right afterthat movement has been initiated by the lost motion connection betweenthe pilot piston 13 and the main control valve 47.

A modified form of fluid pressure operatedapparatus is shown in FIGURE10 which corresponds to VFIG- URE 1. The apparatus is the same as thatshown in FIGURES 1 to 5 except that the reversing piston 24 is returnedto the left-hand end of its travel by a spring 124 after cut-od of thereversing pressure from passage 18, that the travel of the main valve 11to the left is limited by a xed shoulder 125a on a liner retaining ring125, that the lost lmotion means 26, 27, 2S between the main valve 11and the pilot piston 13 are eliminated, the valve 11 abutting the pilotpiston 13 in all positions thereof, and in that the differential piston36 is displaced to the right with respect to the pilot piston 13 by apin 139, which extends from the piston 36 through the main valve 11,coming into contact with the spigot 23 on the reversing piston 24towards the left-hand end of the travel of the main valve 11 and pilotpiston 13.

The operation is the same as in FIGURES 1 to 5, except that in thisconstruction the movement of the diterential piston 36 to the rightrelative to Ithe pilot piston 13 to connect the space between shoulder29 and the head of the pilot piston to vent so equalising the pressureson each side of the head of the pilot piston 13, is eiected first byengagement of the pin 139 with spigot 23 and then by pressure acting onhead 37 of the diierential piston 36, and that on application ofreversing pressure through passage 1S to the reversing piston 24, thespigot 23 enters a recess in the main valve 11 and abuts a shoulder 11ato return the main valve 11 and pilot piston 13 to the positions shownin FIGURE 10. On release of reversing pressure, spring 124 returns thereversing piston 24 to the position shown.

It is to be understood that the invention is not restricted to theprecise constructional details set forth.

yl. Fluid pressure operated apparatus comprising 1n combination (a)valve means comprising a :Erst valve member movable between first andsecond positions,

(b) a pilot piston and a rst cylinder, the pilot piston beingreciprocable in the first cylinder between rst and second positions,

(c) means operative on movement of the pilot piston from its said rstposition to its said second position to move the irst valve member fromits said rst position to its said second position,

(d) a pressure fluid inlet to the irst cylinder on one side of the pilotpiston, through which inlet pressure tluid may be admitted to move thepilot piston from its said first position to its said second position,and

(e) pressure equalizing means operative to equalize the pressure in thefirst cylinder on both sides of the pilot piston, when the pilot pistonis in its said second position,

(f) the said pressure equalizing means being biased against operationand being operated by fluid pressure admitted through said pressure uidinlet.

2. Fluid pressure operated apparatus according to claim l, said pressureequalizing means comprising (a) a second piston and a second cylinder,the second piston being reciprocable in the second cylinder between rstand second positions,

(b) biasing means urging the second piston towards its first position,

(c) lirst ducting interconnecting the part of the rst cylinder on theside of the pilot piston opposite said one side and the second cylinderwhereby -uid pressure from that part of the first cylinder is admittedto the second cylinder to urge the second piston against the biasingmeans towards its second position,

(d) second ducting interconnecting the parts of the rst cylinder on eachside of the pilot piston, and

(e) a second valve member carried by said second Ipiston, and closingsaid second ducting when the second piston is in its said rst position,and opening said ducting when the second piston is in its secondposition.

3. Fluid pressure operated apparatus according to claim 2, the saidpilot piston bounding a bore forming the said second cylinder, and thesaid ducting comprising porting interconnecting the parts of the saidiirst cylinder and the said bore.

4. Fluid pressure operated apparatus according to claim 2, the saidbiasing means comprising a spring.

5. Fluid premure operated apparatus according to claim 2, comprisingabutment means cooperating with the said second piston to limit movementof Ilthe said second piston during movement of the pilot piston from itssaid rst to its said second position.

6. Fluid pressure operated apparatus according to claim 2, the saidducting terminating at one end in porting opening into the said secondcylinder, and the said second piston being operative to close saidporting when in its first position, and to open said porting when in aposition other than its lirst position.

7. Fluid pressure operated apparatus according to claim l, the saidpressure equalizing means comprising (a) ducting interconnecting theparts of Ithe first cylinder on each side of the pilot piston, and

(b) valving operative to open and close said ducting.

8. Fluid pressure operated apparatus according to claim 1, the saidpressure equalizing means comprising (a) ducting connecting the parts ofthe rst cylinder on each side of the pilot piston to atmosphere, and

(b) valving operative to open and close said ducting.

9. Fluid pressure operated apparatus comprising in combination,

(a) valve means comprising a rst valve member movable between first andsecond positions,

(b) a pilot piston and a first cylinder, the pilot piston beingreciprocable in the rst cylinder between first .and second positions,

(c) means operative on movement of the pilot piston from its said rstposition to its said second position to move the valve member from itssaid iirst position to its said second position,

(d) a pressure uid inlet to the rst cylinder on one 'side of the pilotpiston, through which inlet pressure uid may be admitted to move thepilot piston from its said first position to its said second position,

(e) the said pilot piston bounding a bore constituting a secondcylinder,

(f) said pilot piston embodying porting interconnecting the parts of therst cylinder on each side of the pilot piston and the said bore,

(g) the said bore having a part of enlarged diameter,

(h) a second piston reciprocable in the said bore,

lbetween tirst and second positions,

(i) the second piston having a part of enlarged diameter Working in thepart of enlarged diameter,

(j) the second piston carrying a second valve member cooperating withthe porting embodied in the said pilot piston, in its rst position -toprevent com munication via the said bore between the parts of the rstcylinder on opposite sides of the pilot piston, and in -its secondposition to permit such communication,

(k) biasing means urging the said second piston towards its irstposition,

(l) abutment means limiting movement of the second piston duringmovement of the pilot piston between its iirst and second positions,whereby the second piston is caused to move relatively to the pilotpiston during such movement of the pilot piston,

(m) ducting interconnecting the part of the first cylinder on the sideof the pilot piston opposite said one side and the enlarged part of thesecond cylinder,

(n) said ducting terminating in porting in the second cylinder, and thesecond piston being operative to close said porting when in its firstposition, and to open said porting when in a position other than itsrstpositiom; whereby when pressure uid is in the said opposite part ofthe first cylinder and the' second piston, is in a position other thanits rst position, the second piston' is subjected tov pressure againstthe action of the biasing means.

110. Fluid` pressure operated apparatus according. to

claim 9, comprising Y (a) athird piston, and atfhirdvcylinder, thethrdpiston Ibeing reciprocable in thev third cylinder,4 between a iirstpositionvand alsec'on'd position,

(5;) a pressure iuidv inlet tothe third cylinder, whereby pressure fluidmay be admitted to the third cylinder 8:l to move the thirdpiston'frorn` its. iirstV position toitssecond position,

(1c). means operativeY onA movement' ofY theA third pistonV from itssecond position. to its first position when.

the supply of pressure uid'to the third cylinder is cut oi.

References CitedY in the tile of this patent UNITED STATES PATENTSLeonard etV a1; Mar. 1, 1960'.

1. FLUID PRESSURE OPERATED APPARATUS COMPRISING IN COMBINATION (A) VALVEMEANS COMPRISING A FIRST VALVE MEMBER MOVABLE BETWEEN FIRST AND SECONDPOSITIONS, (B) A PILOT PISTON AND A FIRST CYLINDER, THE PILOT PISTONBEING RECIPROCABLE IN THE FIRST CYLINDER BETWEEN FIRST AND SECONDPOSITIONS, (C) MEANS OPERATIVE ON MOVEMENT OF THE PILOT PISTON FROM ITSSAID FIRST POSITION TO ITS SAID SECOND POSITION TO MOVE THE FIRST VALVEMEMBER FROM ITS SAID FIRST POSITION TO ITS SAID SECOND POSITION, (D) APRESSURE FLUID INLET TO THE FIRST CYLINDER ON ONE SIDE OF THE PILOTPISTON, THROUGH WHICH INLET PRESSURE FLUID MAY BE ADMITTED TO MOVE THEPILOT PISTON FROM ITS SAID FIRST POSITION TO ITS SAID SECOND POSITION,AND (E) PRESSURE EQUALIZING MEANS OPERATIVE TO EQUALIZE THE PRESSURE INTHE FIRST CYLINDER ON BOTH SIDES OF THE PILOT PISTON, WHEN THE PILOTPISTON IS IN ITS SAID SECOND POSITION, (F) THE SAID PRESSURE EQUALIZINGMEANS BEING BIASED AGAINST OPERATION AND BEING OPERATED BY FLUIDPRESSURE ADMITTED THROUGH SAID PRESSURE FLUID INLET.